Archives November 2013

Molecularity Of Reaction The molecularity of a reaction simply refers to the number of molecules involved in the rate limiting rate of that reaction. The rate limiting step is the slowest step to take place in the intermediate pathway between the reactants and final products. For example, suppose compounds A and B react to form compound C. The reaction does not necessarily take place in one step. It may be necessary for compound A to first ionize before it can react with compound B, so that the reaction mechanism is:  1. A => A(-) 2. A(-) + B => C There are 2 major steps in the overall reaction of A + B => C. The molecularity of this reaction depends on which of these is the rate limiting step, or which one has a greater energy of activation. (1) If the first step, ionization of A, is rate-limiting (ie it is more...

In a chemical reaction, chemical equilibrium is the state in which both reactants and products are present at concentrations which have no further tendency to change with time. Usually, this state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but equal. Thus, there are no net changes in the concentrations of the reactant(s) and product(s). Such a state is known as dynamic equilibrium.  Heat is energy flowing from a high temperature object to a low temperature object. When the two objects are at the same temperature, there is no net flow of energy or heat. That is why a covered cup of coffee will not be colder than or warmer than the room temperature after it has been in there for a few hours. This phenomenon is known as equilibrium. In more...

In chemistry, a reaction quotient: Qr is a function of the activities or concentrations of the chemical species involved in a chemical reaction. In the special case that the reaction is at equilibrium the reaction quotient is equal to the equilibrium constant. A general chemical reaction in which α moles of a reactant A and β moles of a reactant B react to give σ moles of a product S and τ moles of a product T can be written as   αA + βB is in equilibrium with σS + τT The reaction is written as an equilibrium even though in many cases it may appear to have gone to completion. When a mixture of A and B is made up and the reaction is allowed to occur, the reaction quotient, Qr, is defined as:     where {Xt} more...

A reversible reaction is a chemical reaction that results in an equilibrium mixture of reactants and products. For a reaction involving two reactants and two products this can be expressed symbolically as  ï»¿   A and B can react to form C and D or, in the reverse reaction, C and D can react to form A and B. This is distinct from reversible process in thermodynamics.   The concentrations of reactants and products in an equilibrium mixture are determined by the analytical concentrations of the reagents (A and B or C and D) and the equilibrium constant, K. The magnitude of the equilibrium constant depends on the Gibbs free energy change for the reaction. So, when the free energy change is large (more than about 30 kJ mol−1), then the equilibrium constant is large (log K > 3) and the concentrations of the reactants at equilibrium are very small. Such a reaction is sometimes considered to be an irreversible reaction, more...

The double-slit experiment, sometimes called Young's experiment (after Young's interference experiment), is a demonstration that matter and energy can display characteristics of both classically defined waves and particles, and demonstrates the fundamentally probabilistic nature of quantum mechanical phenomena. In the basic version of this experiment, a coherent light source such as a laser beam illuminates a plate pierced by two parallel slits, and the light passing through the slits is observed on a screen behind the plate. The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen—a result that would not be expected if light consisted of classical particles (i.e., small chunks of matter). However, the light is always found to be absorbed at the screen at discrete points, as individual particles (not waves), the interference pattern appearing via the varying density of these particle hits on the screen. This result establishes the principle known as wave–particle duality. Furthermore, versions of the experiment that include particle detectors at the more...

The Reimer–Tiemann reaction is a chemical reaction used for the ortho-formylation of phenols. The reaction was discovered by Karl Ludwig Reimer and Ferdinand Tiemann. In the simplest case, the product is salicylaldehyde:  The Reimer-Tiemann reaction is an organic reaction used to convert a phenol to an o-hydroxy benzalde-hyde using chloroform, a base, and acid work-up. The mechanism begins with abstraction of the proton from chloroform with the base to form a trichlorocarbanion which spontaneously loses a chloride ion to form a neutral dichlorocarbene. The base also deprotonates the phenol reagent which then attacks the carbene. A series of steps and a final acid work-up result in the o-hydroxy benzaldehyde product.  Mr. Lalit Sardana(IIT-JEE AIR 243) is teaching you Riemer-Tiemann reaction related to JEE Chemistry, he is one of the renowned lecturers in the field of education and he has been playing a more...

  Aldehydes:   1. Definition: Aldehydes are the organic compounds in which carbonyl group is attached to one hydrogen atom and one alkyl or aryl group.   2. General formula: O || C  /  R     H      R can be an alkyl or aryl group.     Ketones:   1. Definition: Ketones are the organic compounds in which carbonyl group is attached to two alkyl group or aryl group or both alkyl and aryl group   2. General formula: O || C  /   R      R’      R, R’ may be alkyl or aryl.   Carboxylic Acids:   1. Definition: Carboxylic acids are the compounds containing the carboxyl functional group (-COOH).   2. General Formula: O || C /    R   OH To get solutions of NCERT problems you can log on to    http://www.studyadda.com/videos/xii-class-chemistry-lectures/chemical-kinetics/determination-of-order/1633 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-8-ncert-solution/1634 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-9-ncert-solution/1635 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-10-ncert-solution/1636 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-11-ncert-solution/1637 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-12-ncert-solution/1638 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-13-ncert-solution/1639 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-14-ncert-solution/1640 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-15-ncert-solution/1641 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-17-ncert-solution/1642 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-16-ncert-solution/1643 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-18-ncert-solution/1644 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-19-ncert-solution/1645 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-20/1646 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-20/1646 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-1-ncert-solution/1647 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-2-ncert-solution/1648 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-3-ncert-solution/1649 http://www.studyadda.com/videos/xii-class-chemistry-lectures/aldehydes-ketones-carboxylic-acids-ncert-solutions/aldehydes-ketones-and-carboxylic-acids-chapter-end-problem-4-ncert-solution/1650 more...

Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous. Several million tons are produced annually as a precursor to PTFE and refrigerants, but its use for refrigerants is being phased out.  Chloroform reacts with 2 atoms of hydrogen to give methylene chloride and similarly chloroform reacts with multiple hydrogen atoms to produce the desired products.  Reduction of Chloroform is a very important topic in chemistry and in this video Mr. Lalit Sardana (IIT-JEE AIR 243) will help you clear your doubts. He has taken up all the related information that is required to help students understand the reduction process. These videos are useful in the JEE mains, JEE Advanced, EAMCET, KCET, WBJEE, etc. Watch the videos now and if you want to see more of these videos subscribe our channel. Reduction more...

When chloroform reacts with nitric acid, nitrochloroform (chloropicrin) and water are formed. Nitration: The hydrogen of the chloroform is replaced by nitro group when it is treated with concentrated nitric acid. The product formed is chloropicrin or trichloronitro methane or nitro chloroform. It is a liquid, poisonous and used as an insecticide and a war gas.   CHCI3 + HONO2    ————→      CNO2 CI3  +  H2O                                      Nitric acid                    Chloropicrin (Tear gas)  Chloropicrin, also known as PS, is a chemical compound currently used as a broad-spectrum antimicrobial, fungicide, herbicide, insecticide, and nematicide. Its chemical structural formula is Cl3CNO2. In agriculture, chloropicrin is injected into soil prior to planting a crop in order to clean the soil of a broad spectrum of fungi, microbes, insects, and other harmful pests. It is commonly used as a stand alone treatment or in combination / co-formulation with methyl bromide and 1,3-Dichloropropene. Mr. Lalit Sardana(IIT-JEE AIR 243) is going to more...

Alkylation of ammonia The reaction of ammonia with an alkyl halide leads to the formation of a primary amine. The primary amine that is formed can also react with the alkyl halide, which leads to a disubstituted amine that can further react to form a trisubstituted amine. Therefore, the alkylation of ammonia leads to a mixture of products.    Mr. Lalit Sardana(IIT-JEE AIR 243) is an IIT-JEE tutor at Sardana Tutorials and he has been bringing up a number of IIT-JEE selections from the city. Many of the students are from Sardana tutorials itself. He owes a million of thanks from his students, as he gave them the strength, to make their dreams come true!.....This video is helpful to the students of 11th CBSE, 12th CBSE, JEE Mains, JEE Advanced, VITEEE, AIPMT, WBJEE, AFMC.   Watch the video now on this link http://www.studyadda.com/videos/jee-chemistry-lectures/amines/preparation-of-mixture-of-amines/1436 If you have more...